Design of synthetic slag

The synthetic slag contains   and with small amount of . The principle component of synthetic slag is lime. Calcium fluoride increases the sulphide capacity of slag and helps fluidizing the slag. Often  is present to deoxidize the molten steel since transfer of sulphur from molten steel to slag is followed by transfer of oxygen from slag to steel. Therefore deoxidation of steel is must for efficient desulphurization. Typically,slag contains and . This slag is pre fused in solid state.

Special synthetic slag can be designed for a specific purpose. For removal of oxide inclusions, a neutral slag with  can be used, when no desulphurization is needed.

Issues related to synthetic slag practice

Synthetic slag practice appears to be simple and not much capital investment is needed. Certain issues are:

i)    Desulphurization may vary from one heat to other if slag carry- over from BOF/EOF is       not controlled. Oxygen content of steel should be same for consistent results.

ii)     is the main component. It is hygroscopic and leads to hydrogen pick up

iii)   Argon bubbling is done to stir the bath. Temperature drop could be of the order of             heat. The temperature drop is resulting from radiation        heat loss from surface and heat transfer due to argon bubbling.

iv)     The slag attacks the ladle refractory. Excessive amount of results in refractory           wear. Higher tap temperature increases refractory wear.